fixes to channelconfig() and write_dochannels().
tested both on droid & linux
25.12.2013 stopped log pushing on usb disconnect.
removed chmod + x from within pull().
stopped recreating databases on modbus failures (tables in memory since
20.12)
26.12.2013 this version to be installed on hvv pumping stations (droid)
switch flight mode if droid on at 20 and 40 s of failing udp send, may help.